JPH06172596A - Polypropylene resin composition, method of coating molding thereof, and coated molding - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a molding which can be top-coated without cleaning with a halogenated organic solvent and is improved in adhesiveness to coating film by mixing PP with a specified elastomer and a specified polycarbonate diol. CONSTITUTION:100 pts.wt. PP is mixed with 20-50 pts.wt. at least one elastomer selected from among an ethylene elastomer, a hydrogenated styrene/butadiene copolymer and a hydrogenated styrene/isoprene block copolymer, 0.3-20 pts.wt. polycarbonate diol of the formula wherein R1 and R2 are each an aliphatic hydrocarbon group; and n is 1-20 and 0-50 pts.wt. inorganic filler to obtain the title composition which can give a molding which can be top-coated directly or after priming or plasma irradiation without degreasing with a halogenated organic solvent and is improved in adhesiveness to coating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition having excellent coatability, particularly an impact-resistant polypropylene resin composition which is preferably used for manufacturing automobile exterior parts such as bumpers, and the polypropylene resin composition. TECHNICAL FIELD The present invention relates to a method for coating a molded product, particularly an automobile exterior part such as a bumper, and a coated molded product.

[0002]

2. Description of the Related Art Polypropylene resin is used in a wide range of applications because it has low specific gravity, high rigidity, and excellent heat resistance and chemical resistance. However, it is known that polypropylene resin is originally non-polar and therefore inferior in coatability. For example, when coating a polypropylene automobile bumper, in order to obtain sufficient adhesion strength of the coating film,
It has been necessary to perform degreasing cleaning with a halogen-based organic solvent such as 1,1-trichloroethane, and then undercoat a primer or perform plasma irradiation treatment and then topcoat.

[0003]

However, the conventional coating method as described above has many steps and is uneconomical in terms of time. Further, there is concern that the halogen-based organic solvent used for degreasing and cleaning may adversely affect the human body and the environment. 1,
1,1-Trichloroethane (hereinafter referred to as trichlene) has been shown to destroy the global environment, especially the ozone layer.
It was resolved in 2005 at a monthly Montreal conference to ban its manufacture and use globally. That this solution is not an easy task is clear from the fact that a grace period of 15 years has been set.

However, the rate of destruction of the global environment is high thereafter, and it has been decided that the latest implementation of the 1996 and 10 years ahead of schedule should be resolved and the solution should be made very urgently. Moreover, it is a difficult task.

Further, there is a strong demand for improvement of the conventional coating method in consideration of the time and cost spent for the treatment of waste liquid after coating.

Further, as for gasoline used for automobiles, gasoline containing methyl-tert-butyl ether and the like is used since conventional so-called hydrocarbon compounds are the only components, and the demand for solvent resistance of automobile parts is further increased. The current situation is that it is becoming stricter.

Thus, there is a demand for the development of a method for coating automobile parts and a resin composition for automobile parts which does not require treatment with trichlene for painting.

In order to improve the coatability of a molded article composed of a composition containing polypropylene and an elastomer as main components,
A method of adding a diene polymer having a hydroxyl group at the terminal or a hydrogenated product thereof has been proposed. (JP-A 3-1
57168, JP-A-3-277636, and JP-A-4-77.
567, JP-A-4-93330, etc.). However, these methods aim to apply the paint without applying primer coating or plasma treatment.If degreasing cleaning with trichlene is not performed, solvent resistance is poor, and more severe paintability evaluation is required. There was a problem.

Further, in North America, South America and Europe, methanol has been recently added to automobile gasoline from the viewpoint of resource saving and cost reduction.
So-called gasohol, which is a mixture of lower alcohols such as ethanol and butanol, tends to be used. Gasohol has a greater effect on the peelability of the coating film than gasoline alone, and there is a demand for improved gasohol resistance.

The object of the present invention is to eliminate the need for degreasing and cleaning with a halogen-based organic solvent such as trichlene, and to carry out a top coat directly or after a primer coating or plasma irradiation treatment, and the adhesion strength of the coating film. To provide an impact resistant polypropylene resin composition capable of obtaining a molded product having significantly improved impact resistance, and particularly an impact resistant polypropylene resin composition having excellent paintability, which is suitably used for manufacturing automobile exterior parts such as bumpers. To provide things.

Another object of the present invention is to provide an improved coating method for a molded article obtained by molding the above resin composition.

Still another object of the present invention is to obtain a molded article obtained by coating by the above-mentioned coating method, particularly adhesion strength and gasoline resistance of coating film and gasohol resistance (solvent resistance to a mixture of gasoline and oxygen-containing compound). It is to provide automobile exterior parts with excellent performance.

[0013]

According to the present invention, (A)
100 parts by weight of polypropylene, 20 to 50 parts by weight of (B) an ethylene-based elastomer, at least one elastomer selected from hydrogenated styrene / butadiene copolymers and hydrogenated styrene / isoprene block copolymers, and (C) the following structure formula (I) HO - (- R 1 -O-CO-O-) n -R 2 -OH (I) ( wherein R ₁ and R ₂ are represented by an aliphatic hydrocarbon radical, n
Is a whole number of 1 to 20) and a polycarbonate resin represented by 0.3 to 20 parts by weight and (D) an inorganic filler of 0 to 50 parts by weight.

According to the present invention, a molded product obtained by molding the above polypropylene resin composition is directly or primer-coated or plasma-treated without degreasing and cleaning with a halogen-based organic solvent, and then overcoated. A coating method is provided that comprises performing painting.

Further, according to the present invention, there is provided a coated molded article obtained by coating a molded article using the above polypropylene resin composition by the above method.

The polypropylene as the component (A) used in the present invention may be a homopolymer of propylene or a random or block copolymer of propylene and ethylene and / or α-olefin as long as it is crystalline polypropylene. . The α-olefin referred to here is butene-1, pentene-1, hexene-1, 4-methylpentene-1 and the like, and one or more of these can be used.

In the present invention, a block copolymer of propylene and ethylene is preferably used. For example, the ethylene content is 2 to 25% by weight, and the melt index (MI) is 1 to 100 g / 10 min (ASTM.
D-1238, 230 ° C) can be particularly preferably used.

The component (B) elastomer used in the present invention is at least one elastomer selected from ethylene-based elastomers, hydrogenated styrene / butadiene copolymers and hydrogenated styrene / isoprene block copolymers.

As the ethylene-based elastomer, a random copolymer rubber of ethylene and propylene (hereinafter abbreviated as EPM), a ternary copolymer rubber of ethylene-propylene-diene (hereinafter abbreviated as EPDM), ethylene-butene- 1 copolymer rubber, ethylene-propylene-butene-
1 copolymer rubber may be mentioned.

EPM and / or EPDM are preferably used, and more preferably EPDM or EPM and EP.
A mixture of DM is used.

The above EPM has a propylene content of 10
-60% by weight, preferably 15-60% by weight, more preferably 20-55% by weight, Mooney viscosity ML _{1 + 4} (1
(00 ° C.) is 10 to 80, preferably 15 to 60, and more preferably 20 to 50.

The above EPDM has a propylene content of 1
0-60% by weight, preferably 15-60% by weight, more preferably 20-55% by weight, Mooney viscosity ML
_{1 + 4} (100 ° C) is 10 to 80, preferably 15 to 6
It is 0, more preferably 20 to 50. Iodine value is 5
-30, preferably 7-25, more preferably 8-2
A polymer having a molecular weight distribution Mw / Mn of 0 to 1.5 to 4.0 can be used.

The above Mw / Mn is a value measured by gel permeation chromatography. Also, the above E
As the diene component in the PDM, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene and the like can be used.

In the present invention, more preferably, the propylene content is 15 to 25% by weight and the Mooney viscosity ML.
_{1 + 4} (100 ° C.) EPM of 15 to 25, propylene content of 20 to 30% by weight, Mooney viscosity ML _{1 + 4} (1
EPDM having a temperature (00 ° C.) of 35 to 45, an iodine value of 10 to 15 and a molecular weight distribution Mw / Mn of 1.5 to 2.5 can be preferably used.

The component (C) polycarbonate diol used in the present invention is represented by the above structural formula I,
It has an aliphatic carbonate skeleton and has hydroxyl groups at both ends.

In formula I, R ₁ and R ₂ are preferably C
It is a group represented by _m H _2m (where m is an integer of 1 to 10).

In particular, the molecular weight is 500 to 3000, preferably 600 to 2000, more preferably 700 to 150.
Viscosity at 0 and 75 ° C is 100 to 3000 cS, preferably 150 to 2500, and more preferably 200 to 1000.
Those which are liquid, solid or semi-solid at 20 ° C. can be used, and those which are solid are particularly preferable. The hydroxyl value is 20 to 300 KOHmg / g, preferably 30 to 200 KOHmg / g, and more preferably 35.
~ 150 KOHmg / g.

The amount of the polycarbonate diol as the component (C) used is 0.3 to 20 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 0. 7 to 7 parts by weight.

In the present invention, an inorganic filler can be used as the component (D). As the inorganic filler, for example, calcium oxide, magnesium oxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, magnesium carbonate, calcium silicate, magnesium silicate,
Calcium sulfate, calcium carbonate, barium sulfate, calcium sulfite, talc, clay, glass, mica, basic magnesium carbonate, dolomite, wollastonite,
Further, whiskers such as calcium titanate and magnesium sulfate can be mentioned, but in consideration of the balance between impact strength and rigidity, it is particularly preferable to use calcium carbonate, barium sulfate or talc. Considering the impact resistance of the resulting composition, the inorganic filler used in the present invention preferably has an average particle size of 5 μm or less.

The inorganic filler used in the present invention is preferably a surface-treated one, and the surface treatment is carried out by a known method, for example, various silane-based or titanate-based cups. A ring agent, a higher fatty acid type, or an unsaturated organic acid type surface treatment agent can be used. When such a surface treatment is applied, in addition to the effects of the present invention,
It is effective for improving physical properties such as kneading property, moldability, self-tapping strength, and weld strength.

The amount of the inorganic filler used is 0 to 50 parts by weight per 100 parts by weight of (A) polypropylene, and 10 to 50 parts by weight, preferably 10 to 10 parts by weight for automobile exterior parts and the like.
35 parts by weight.

Furthermore, one of the preferred embodiments of the present invention is (A) polypropylene, (B) propylene content of 15 to 50% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.).
Of 20 to 60, iodine value of 8 to 25, and molecular weight distribution Mw
/ Mn is 1.5-4.0 ethylene-propylene-
A diene terpolymer rubber, (C) a polycarbonate diol represented by the structural formula I and (D) an inorganic filler, and the content of the component (B) is based on the total weight of (A) + (B). And the content of the component (C) is 0.5 to 10 based on the total weight of (A) + (B) + (C).
The content of the component (D) is (A) + (B) +.
The present invention relates to a polypropylene resin composition, wherein the total weight of (C) is 0 to 40 parts by weight per 100 parts by weight.

In the present invention, in addition to the components (A) to (D) described above, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and a low-density polyethylene in an amount within a range not significantly impairing the effects of the present invention, One kind or two or more kinds of ultra-low density polyethylene can be used.

Further, in the present invention, a compound having an OH group other than polycarbonate diol, such as polyhydroxypolyolefin, can be used in combination in an amount within a range that does not significantly impair the effects of the present invention.

Further, if necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, a flame retardant, a nucleating agent, a processability improving agent, a lubricant, an antistatic agent, which are generally used for olefin polymers, and Additives such as pigments can be used.

The polypropylene resin composition of the present invention is mixed with a Henschel mixer or the like which is generally used in the art, and then mixed with a single screw extruder, a twin screw extruder, a roll, a Banbury mixer or the like. It is manufactured by kneading and pelletizing.

The resin composition thus obtained can be molded into a predetermined molded product by a commonly used molding method such as an injection molding method, an extrusion molding method and a compression molding method.

In the coating method of the present invention, the above polypropylene resin composition is molded, and the surface of the molded product obtained is directly or without primer cleaning with a halogen-based organic solvent, primer coating or plasma irradiation treatment. And then
After that, it comprises a step of applying a top coat.

In this coating method, degreasing cleaning with a solvent other than the halogen-based organic solvent can be carried out if necessary. Solvents other than halogen-based organic solvents here include lower alcohols such as isopropyl alcohol,
Examples thereof include a surfactant-containing alkaline or acidic aqueous solution.

As the primer for the undercoat in the coating method of the present invention, for example, a commercially available acrylic-chlorinated polypropylene type primer for polypropylene can be used. After preparing the primer according to the specifications, for example, coating is performed so that the film thickness is about 10 μm.

In the coating method of the present invention, as the top coat paint, various paints such as a two-pack type urethane paint, a one-pack type alkyd-melamine paint and a one-pack type acrylic paint can be used, but especially at a low temperature ( For example, the effect of the resin composition of the present invention is remarkable for improving the gasoline resistance and gasohol resistance of a molded article coated with a urethane coating composition of 80 ° C.).

In the method of the present invention, the topcoat paint can be directly applied without using the primer for undercoating, but it is preferable to use the primer for undercoating in order to impart solvent resistance to the coating film.

[0043]

EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention.

The contents of each component used in each resin composition will be described below. PP-A: crystalline ethylene-propylene block copolymer (ethylene content 9.0% by weight, MI (230
(° C) 22 g / 10 minutes) PP-B: crystalline ethylene-propylene random copolymer (ethylene content 4.5% by weight, MI (230)
15 ° C.) 15 g / 10 min) EPDM-A: Propylene content 40% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.) 39, diene component ethylidene norbornene, iodine value 15, molecular weight distribution Mw / Mn Is 2.2, ethylene-propylene-diene terpolymer rubber EPDM-B: propylene content is 25% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.) is 40, diene component is ethylidene norbornene, Ethylene-propylene-diene terpolymer rubber having an iodine value of 14 and a molecular weight distribution Mw / Mn of 2.3 EPM-A: propylene content of 45% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.) 28, which is ethylene-
Propylene copolymer rubber EPM-B: ethylene having a propylene content of 20% by weight and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 23.
Propylene copolymer rubber Polycarbonate diol: Nippon Polyurethane Industry Co., Ltd., Niprolan N-981 [molecular weight = 990, viscosity (75 ° C.) = 330 cS] Talc: average particle diameter 2 μm Examples 1 to 7, Comparative Example 1, Reference Example After mixing the above raw materials in the proportions shown in Table 1 by a Henschel mixer, they were melt-kneaded by a twin-screw extruder set at 210 ° C. and pelletized to obtain a resin composition.

Flexural modulus was measured according to ASTM D790, Izod impact strength (with notch) was ASTM
It was measured at a temperature of 23 ° C and -40 ° C according to D256.

A test piece used for the coating film adhesion test was prepared as follows. Test piece by injection molding (80 × 2
40 mm, thickness 3 mm) was coated with a primer (manufactured by Nippon Bee Chemical Co., Ltd., trade name: RB-150) to a film thickness of 10 μm, dried at 80 ° C. for 10 minutes, and then a urethane metallic paint was applied to the primer surface. (Manufactured by Nippon Bee Chemical Co., Ltd., trade name: R-212) and urethane clear coating (manufactured by Nippon Bee Chemical Co., Ltd., trade name: R-213) were prepared according to the specifications specified by Nippon Bee Chemical Co. Apply 20μm and 30μm respectively, 8
It was dried at 0 ° C. for 30 minutes and then left for 48 hours to obtain a test piece.

On the coating surface of the obtained coated article, 100 * 10 grids were cut at 1 mm intervals, and the cellophane tape completely adhered to the grids by finger pressure was rapidly peeled off at an angle of 45 [deg.]. After repeating this operation twice, the ratio of the cross-cuts of the remaining coating film was determined.

Also, make sure that the cross section of the coated product is the same.
The time until the material cut into a size of 0x30 mm is immersed in gasoline and gasohol (gasoline containing 10% by volume of ethyl alcohol) at 23 ° C and abnormalities (peeling, swelling, wrinkles) are observed in the coating film. Was measured.

The results are shown in Table 1. The 1,1,1-trichloroethane steam cleaning in Reference Example was performed by exposing the molded product to 1,1,1-trichloroethane saturated steam for 30 seconds. Then, it dried and it moved to the coating process of a primer, and the same operation as the above was performed below.

[0050]

[Table 1] Example 8 Using the composition of Example 1, a test piece similar to that of Example 1 was prepared. This test piece was directly applied with the urethane metallic paint and urethane clear paint used in Example 1 without applying 1,1,1-trichloroethane vapor cleaning and without applying a primer. No peeling was observed in the cross-cut test. Comparative Example 2 The composition of Comparative Example 1 was used and coating was carried out in the same manner as in Example 8. Full-scale peeling occurred in a cross-cut test.

[0051]

EFFECT OF THE INVENTION The polypropylene resin composition of the present invention can provide a coated molded article having good adhesion of the topcoat paint without washing with a halogen-based organic solvent, and has high industrial utility value.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08K 5/10 KEQ 7242-4J // (C08L 23/10 69:00 9363-4J 23:16) (72) Inventor Takeaki Inokuma 1190, Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Chihiro Ogawa 1190, Kasama-cho, Sakae-ku, Yokohama, Kanagawa Mitsui Toatsu Chemical (72) Inventor Osamu Aoki 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Honda R & D Co., Ltd. (72) Inventor Kenji Hamahae 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Honda R & D Co., Ltd (72) Inventor Atsushi Takeuchi, 1-4-1, Chuo, Wako, Saitama Stock Company, Honda R & D Co., Ltd.

Claims (6)

[Claims] 1. At least one elastomer selected from (A) 100 parts by weight of polypropylene, (B) ethylene elastomer, hydrogenated styrene / butadiene copolymer and hydrogenated styrene / isoprene block copolymer. part, (C) the following structural formula (I) HO - (- R 1 -O-CO-O-) n -R 2 -OH (I) ( wherein R ₁ and R ₂ are represented by an aliphatic hydrocarbon group A polypropylene resin composition comprising 0.3 to 20 parts by weight of a polycarbonate diol represented by the formula (1) and 0 to 50 parts by weight of an inorganic filler (D). 2. The polypropylene resin composition according to claim 1, wherein the ethylene-based elastomer is a random copolymer rubber of ethylene and propylene and / or a terpolymer rubber of ethylene-propylene-diene. 3. The polypropylene resin composition according to claim 1, wherein the polycarbonate diol represented by the structural formula [I] has a molecular weight of 500 to 3000 and a viscosity at 75 ° C. of 200 to 3000 cS. 4. (A) polypropylene, (B) propylene content 15 to 50% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.) 20 to 60, iodine value 8 to.
25, and the ethylene molecular weight distribution Mw / Mn of 1.5 to 4.0 - propylene - diene ternary copolymer rubber, (C) the following structural formula (I) HO - (- R 1 -O-CO- O-) _n -R ₂ -OH (I) (wherein R ₁ and R ₂ are each represented by an aliphatic hydrocarbon group, and n
Is an integer of 1 to 20), and (D) an inorganic filler, and the content of the component (B) is 10 to 60% by weight based on the total weight of (A) + (B). The content of the component (C) is 0.5 to 10% by weight based on the total weight of (A) + (B) + (C), and the content of the component (D) is (A) + ( B) + (C) 0 to 40 parts by weight per 100 parts by weight of total weight, polypropylene resin composition 5. The polypropylene resin composition according to claim 1 is molded, and the surface of the resulting molded product is directly or primer-coated or plasma-treated without top-coating with degreasing cleaning with a halogen-based organic solvent, and then topcoating is performed. A method for coating a molded product of a polypropylene resin composition, comprising: 6. A coated molded article obtained by the method for coating a molded article of the polypropylene resin composition according to claim 5.